Plant Disease and Defence
Signs of Plant Disease
Signs of Plant Disease Possible Cause
Stunted Growth Mineral deficiency, the plant can’t get enough minerals
Spots on Leaves Fungal leaf spot – fungal disease
Rot Excess of water
Growths Fungi, bacteria viruses and insect infection
Malformed Leaves and Stems Chromosome imbalances
Discolouration and Chlorosis Poor drainage, damaged roots, high alkalinity, mineral deficiency
Presence of Pests Certain plants can attract them, and dark damp conditions
Diseases
Dutch Elm Disease – member of sac fungi affecting elm trees, spread by elm bark beetles
can caused leaves to wilt, droop, curl and turn brown.
Tobacco Mosaic Virus – virus that affects lots of plants, especially tobacco plants, it causes
discolouring of leaves and mosaic like malting.
Potato Blight – caused by fungus, spreads through air when its warm and humid, it causes
brown ulcers on stem and leaves rot.
Rose Black Spot – caused by a fungus, the leaves turn yellow with black patches and fall off.
Defences
Plants use a range of defences (adaptations to fight off pathogens).
Chemical Defences:
toxins and enzymes
toxic metabolites which are lethal to animals
Mechanical Adaptations:
impenetrable barrier such as bark and waxy cuticle causes animals rashes and allergic
reactions
Mineral Ions
The minerals a plant need are:
Nitrate
Phosphate
Potassium Ions
Magnesium Ions
Signs of Plant Disease
Signs of Plant Disease Possible Cause
Stunted Growth Mineral deficiency, the plant can’t get enough minerals
Spots on Leaves Fungal leaf spot – fungal disease
Rot Excess of water
Growths Fungi, bacteria viruses and insect infection
Malformed Leaves and Stems Chromosome imbalances
Discolouration and Chlorosis Poor drainage, damaged roots, high alkalinity, mineral deficiency
Presence of Pests Certain plants can attract them, and dark damp conditions
Diseases
Dutch Elm Disease – member of sac fungi affecting elm trees, spread by elm bark beetles
can caused leaves to wilt, droop, curl and turn brown.
Tobacco Mosaic Virus – virus that affects lots of plants, especially tobacco plants, it causes
discolouring of leaves and mosaic like malting.
Potato Blight – caused by fungus, spreads through air when its warm and humid, it causes
brown ulcers on stem and leaves rot.
Rose Black Spot – caused by a fungus, the leaves turn yellow with black patches and fall off.
Defences
Plants use a range of defences (adaptations to fight off pathogens).
Chemical Defences:
toxins and enzymes
toxic metabolites which are lethal to animals
Mechanical Adaptations:
impenetrable barrier such as bark and waxy cuticle causes animals rashes and allergic
reactions
Mineral Ions
The minerals a plant need are:
Nitrate
Phosphate
Potassium Ions
Magnesium Ions
